Radio Receiver

RF Amplifiers and Antenna Systems

Radio Receiver

In radio communications, an electric radio receiver, usually called a simple radio, an on-off or a wireless radio, is a simple electronic device that receives radio signals and converts them into a usable form. It is commonly used with an antenna attached to it. Radio receivers come in many shapes and sizes and operate in different ways. It may be used as a general purpose receiver or may have specialized channels to receive certain frequencies. It is necessary to choose the type of receiver depending on the kind of signal to be received.


Radio receivers are designed in the form of a transceiver so that they receive and decode radio signals and convert them into electronic pulses which can be understood by a circuit. A circuit is made up of components such as a source, an electrode and an insulator. The source is usually a magnet which has to be magnetized or a conductive metal such as copper or even stainless steel. The second component is the capacitor which is charged and acts as an electric charge.


Capacitor based radio receivers are generally used in the telecommunications industry. A radio transmitter uses an antenna to send radio waves to the capacitor and converts them into electrical pulses which are then amplified by a mixer. The output from the capacitor changes the frequency of the radio receiver, which in turn changes the frequency of the transmitted radio waves. This process is repeated many times, making the receiver converts the radio waves into a suitable waveform for transmission over the airwaves.


This process is also called capacitive detection where the receiver transmitter is sensitive to any change in the capacitance of the charged capacitor. It senses the change in capacitance caused by the radio waves. If there is a radio wave that produces a frequency lower than the one the receiver is sensitive to, it will not work. To overcome this difficulty manufacturers have devised a special filter which allows the signal strength to fluctuate. The fluctuation will allow the radio waves to be transmitted over the air without being affected.


On the other hand, RF amplifiers can use a separate configuration of diodes and transistors for producing stronger signals. The main advantage of using an RF amplifier is that it produces much stronger signals than a simple Radio Receiver. However, the main disadvantage is that it is much more expensive. In addition, the RF signal must travel through the entire range of frequencies to generate strong signals. The efficiency of RF amplifiers is also dependent on the signal strength thus, it is necessary that the input signal strength is adequate.


Amplifiers that use phase shifting or pulse width modulation (PWM) are more effective than their Capacitor based counterparts. They are able to produce lower audio output voltages because they operate in a lower output and power spectrum. PWM works by switching the input audio frequency from one to another as frequency is shifted by a certain amount. Frequency shifting allows the output voltage to vary as needed and thereby produces much stronger signals. Some of the advantages of using PWM are that it can be used with any type of audio source and that it generates lower audio output voltage.

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